Compact dual-band bandpass filter using defected SRR and irregular SIR

A novel miniaturised dual-band bandpass filter (BPF) based on defected split-ring resonators (SRRs) and irregular stepped-impedance resonators (SIRs) is proposed. By applying defected SRRs embedded with eight combinations of three whole or broken grooves, which are formerly used for divination, the passband of 2.35–2.52 GHz with wideband harmonic suppression is achieved for WLAN applications. To create one more passband of 5.09–5.3 GHz, the irregular SIRs are etched inside the defected SRRs. Finally, such a prototype is designed and fabricated with the dimension of only 20 × 20 mm2 (0.27λg × 0.27λg). The measured results of this dual-band BPF agree well with the simulations verifying the proposed idea.